Modern technologies are developing prosperously. Novel information products are introduced for satisfying the diversified needs of many people. Early displays are mainly cathode ray tube (CRT) displays. They have huge size and consume a great deal of power. In addition, the radiation they produced is harmful to the health of long-term users. Accordingly, the CRT displays in the market are gradually replaced by liquid crystal displays (LCDs), which have the advantages of small size, low radiation, and low power consumption and hence have become the mainstream of the market.
LCDs are a kind of flat panel displays (FPDs) having light and thin outlines. Thanks to their advantages of low radiation, small volume, and low power consumption, they have gradually replaced the traditional CRTs and applied extensively to information products such as notebook computers, personal digital assistants (PDAs), flat-screen TVs, or mobile phones. An LCD comprises a liquid crystal panel, a timing controller (ICON), a gate driver, and a source driver. The TCON is used for producing image data signal and driving the control signal and timing signal required by the liquid crystal panel. The gate driver is used for producing the scanning signal for turning on or off the pixel circuit array. Besides, the source driver produces the driving signal of the liquid crystal panel according to the image data signal, the control signal, and the timing signal.
Current driver chips of liquid crystal panels are developing towards high resolution; each stage of source is output by an operational amplifier for driving the load. Because high resolution requires more operational amplifiers, there will be a substantial static current produced by the operational amplifiers. For solving the problem, the only method is to limit the static operational current of the operational amplifier within a very small range. Nonetheless, the operational amplifiers according to the prior art adopt the floating source follower method to control the output static current. Under this architecture, the operational amplifiers tend to output excessive static current owing to process variations, and thus leading to excessive static power consumption.
Accordingly, the present invention provides a novel operational amplifier capable lowering power consumption effectively. The problem described above can hence be solved.